Abstract

We experimentally demonstrate a new type of add–drop filter incorporating an asymmetric Y-branch waveguide coupler and a shifted-grating mode-conversion cavity. The device relies on mode separation in the asymmetric Y-branch and wavelength-selective mode conversion upon reflection from the shifted-grating cavity. Add–drop functionality is demonstrated in a three-port integrated silicon-on-insulator device.

Figures (5)

(a) ADF schematic showing MCC and asymmetric Y splitter. (b) Fabricated device with partial views of the asymmetric Y splitter and the shifted-grating MCC (not to scale); the MCC utilizes two sets of silicon/air grating mirrors, each having two λ/4=387nm air gaps, a single 5λ/4nSi=556nm silicon slab, and a ΔG=5λG/4nSi=556nm grating shift at x=0. (c) FDTD simulation of the cavity power with a TM1 incident at the input shifted grating. The waveguide widths are WIN=4μm, WTHRU=8μm, and WDROP=12μm.

FDTD simulations of the ADF MCC: (a) ADF MCC spectrum including waveguide propagation and mirror losses, (b) “ideal” ADF MCC spectrum with no loss. The shaded area in (b) corresponds to the resonance near the grating shift design wavelength, λG. The dip and spurious peak just to the left of the DROP resonance near λG in (b) may be attributed to incomplete TM0–TM1 mode conversion.